The invention concerns an eccentric screw pump having a pump shaft which at one end is in the form of a hollow shaft mounted near a joint head or the like connecting portion and connected thereto, and which is fitted on to the output shaft of a pump drive and is connected thereto.
The applicants DE 41 21 717 discloses an eccentric screw pump of that kind. Its pump connection shaft which is hollow towards its end is pushed on to the output shaft and connected thereto in positively locking relationship by a grooved dowel pin which crosses the shaft axis. The direct connection of the output shaft of the pump drive to the drive shaft of the pump, which is fitted on to same, can also be effected by spline connections.
For assembly and dismantling reasons those connections involve play and are protected from corrosion by additional sealing elements. In spite of that sealing effect and the use of anti-corrosion agents between the components it is not possible to exclude corrosion, in particular frictional or fretting corrosion or tribocorrosion.
In addition, by virtue of their design configuration, as a result of stress concentrations or notch effects which occur, those connections require large outside diameters for the pump shaft, with the consequence that they necessitate in particular shaft sealing components of greater size, in comparison with a pump without a push-on shaft connection, and that gives rise to an increased level of susceptibility on the part of such components.